Electbicai ighitioh system



Aug. "i, w23 194mm@ H. M. MULLER ELECTRICAL IGNITION SYSTEM Filed Sent. 15 1921 O o O Patented hing. 7, i923.

HUGH M. STOLLER, OIF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC 00ml?,

moonrona'rnn, or new Yoan, n.

Y., A CORFORATXON 0F NEW YGRlK.

ELECTIRJECAL IGNITION SYSTEM.

Application led September To all whom t may concern:

Be it known that I, HUGH M. STOLLER a citizen of the United States, residing at New York city, in the county of New York and State of New York, have invented certain new and useful improvements in Electrical Ignition Systems, of which the following is a full, clear, concise, and exact description.

rifhis invention relates to improvements y in electrical ignition systems and more particularly to such systems employed for igniting the 'gaseous charges in internal combustion engines. I

One of the objects of the invention is to provide an ignition system, energized by a current of relatively high voltage, which will deliver a spark only when the primary circuit is broken, and will not deliver a spark when the said circuit is closed.

'llhere are now in genera-l use, electric power and light plants comprising an internal combustionv engine and a dynamo driven thereby. in order to make the control circuits for such plants as economical and simple as possible, it has been the practice to supply the ignition system of the intcrnal combustion engine with current from the dynamo. rihe current supplied by such dynamos is generallyunder a pressure of approximately thirty-two volts or more, and,`due to this potential, for reasons hereinater explained,lgreat diiculty has been encountered in preventing ak spark being delivered the spark plug of the engine when the primary ignition circuit is made; this spark occurring at a time too early in the cycle of the engine for eiiicient operation. rihis difiiculty is obviated by the' present invention which is an improvement upon the invention disclosed in the copending application of Reddig, Serial No. 465,296, tiled April 28, 1921.

'in ignition systems employed in such plants which comprise a primary circuit which is made and broken intermittently by an interrupter, and a secondary circuit inductively related to the primary circuit in which the spark plug of the engineJ is connected, the eficiency and lite of the en; gines have been reduced, due to the presence of what is known in the art as pre- 15, 1921. Serial N0. 500,786.

ignition. iin the ecient operation of an internal combustion engine, the gaseous charge should be fully ignited at a time when the piston has about completed its compression stroke and has just begun its working stroke, at which time the connecting rod has just passed dead center. it the charge is fully ignited before the piston has reached this point in its cycle, the force of the explosion will be exerted there-against either while it is completing its compression stroke or isgon dead center; in both cases lessening the e'ective working power oit the explosion and in the second case placing an undue strain on the connecting rodr and crank shaft. Where a gaseous charge is ignited at such a time preignition is said to have taken place. Upon careful analysis it has been found that preignition which has been prevalent in ignition systems ot the type above referred to, has been caused by the creation of a spark at the plug when the interrupter closes the primary circuit. in such ignition systems it is desired that a spark take place at the plug at the time when the interrupter breaks the primary circuit, and Where such a spark occurs at the plug when the primary circuit is closed by the interrupter, the charge is fired too early in the cycle of the engine. it is a primary object of the invention to provide anl ignition system of this type which will prevent any spark occuring at the plug when .the interrupter closes the primary circuit, and will not increase to any substantial degree the potential required to be induced in the secondary circuit in order to produce a spark at the plug when the primary circuit is broken. 'loy accomplish this object, an ignition system made in accordance with the invention includes an asymmetric conductor such as an electron tube, a tungar rectifier, etc., in its secondary circuit, the anode and cathode of which are so arranged with respect to the current tlow that itprevents all current flow through said secondary circuit when the primary circuit is made and permits current to flow only when the primary circuit is broken.

in the drawings, the iigureillustrates a preferred embodiment of the invention. 'Referring to the drawings in detail, the

reference numeral 1 indicates an internal combustion engine connected with a dynamo electric machine 2 by means of a shaft 3, the dynamo when in operation serving to energize a series of translating devices 4, and charge a storage battery 5. The dynamo 2 is provided with a shunt winding 6 and a series winding 7 thus making it a compound machine. -otatably mounted upon the shaft 8, is a cam 8 having an extension 9 which cooperates with a contact 10 to periodically interrupt the primary circuit. A manual switch 11 serves as a means for starting and stopping the operation of the system. y

A low tension primary winding 12 has in series therewith a resistance 13 to'y prevent an excess of current flow, and the filament 14 of an asymmetric two element conductor or valve 15. When the interrupter closes its contact, a circuit through the primary winding 12 is established as follows: positive pole of dynamo 2, conductors 16, 17,

and 18, winding 12, resistance 13, conductor 25. In series with the winding 24 is the plate 26 of the valve 15.

The operation of the system is as follows: When the primary circuit is made, the voltage induced in the secondary circuit is in the direction indicated by the dotted line arrow, and at this time no induced current can flow through the winding 24 because of the asymmetric action of valve 15, the characteristics of which are well known to those skilled in the art. When contact 9 leaves Contact 10 and the circuit of winding 12 is accordingly broken, the voltage induced in secondary winding 24 is in the opposite direction, as indicated by the fullA line arrow, and produced a spark at the terminals of the plug 25 over the following circuit: winding 24, conductor 27, plate 26, filament 14, conductor 19, resistance 13, primary winding 12, conductor 18, 17, series field 7, battery 5, manual switch 11, conductors 22 and 28, through the frame of' engine 1, spark plug 25, conductor 29, and' back to the coil 24.

rIlhe necessity for providing the above described means for preventing pre-ignition is greater in cases of relatively high voltage ignition systems operating at thirty-two volts and over as compared with low voltage systems operating at twelve volts and under. In order to secure a satisfactory life of the breaker contacts 9 and 10, it is necessary to limit the inductance of the `primary winding 12 by employing a low resistance winding. It is, therefore, necessary to insert the resistance 13 to limit the primary current. The ratio of resistance to inductance in the primary circuit of such high voltage ignition systems, is, therefore, large, resulting in a relatively quick building up of current, and, therefore, of secondary voltage. Thus, in such high voltage systems, the ratio of the induced voltage in the secondary upon the make of the primary contacts, as compared to the break, is greater than in low voltage ignition systems. y l

The difficulties of securing proper ignition in prime mover dynamo plants are further increased at starting by the fact that the primary battery voltage is reduced by the heavy current required to crank the engine, the generator at that time operating as a motor. The tendency to pre-ignition is also increased toward the latter part of the charging period when the battery voltage and consequently the secondary voltage is hi h.

gis is well `known in the art, the potential required to break down a spark gap is much less at high temperatures and when the gap is located in a gas, such as is formed by the explosive mixture. It is obvious, however, that under starting conditions when the engine is cold and the explosive mixture is imperfectly vaporized', that the potential necessary to cause a spark to cross the gap at the spark plug will be very much greater than under runningconditions when the engine is warmed up. The result is that the use of an asymmetric conductor of this type prevents ignition which would otherwise occur after the engine has warmed up, but at the same time consumes but a small proportion of the voltage of the secondary circuit which is especially advantageous under the conditions occurring at starting which require the maximum induced voltage in the seconda-ry circuit.

Although this system is disclosed in connection with prime mover dynamo plants, its application is not to be considered as' limited to such plants, but is to be defined solely by the scope of the appended claims.

What is claimed is:

1. In a system for preventing preig'nition in explosive engines, a-low tension circuit including a source of current under pres-v sure of a relatively high voltage and an terruoter, a high tension circuit in inductive relation to the low tension circuit and' including a spark gap, and a hot cathode asymmetric conductor in the secondary circuit for passing currents resulting from the opening of the interrupter contacts.

2. In a prime mover dynamo plant in combination, a single cylinder internal combustion engine, a generator driven by the engine, supply leads from the generator, an induction coil primary and an interrupter connected across the leads of the generaiin Witness whereof, ii hereunto subscribe il@ tor, a secondary in inductive relation to the my name this 10th day of September A. D.,

primary, a spark plug, and a hot cathode 1921.

asymmetric conductor in circuit with the secondary to prevent current passing 'therethrough upon the closure of the interrupter contacts. Y

HUGH M. STLLER. 

